The present invention relates to a method of producing a pattern-formed structure, which structure is less likely to deteriorate as time elapses after the characteristic thereof is modified by using a photocatalyst, because no pyotocatalyst exists in the resulting pattern-formed structure. The present invention also relates to a photomask which can be used in the aforementioned method of producing a pattern-formed structure.
As the conventional method of forming a highly elaborate pattern, is generally known a method of producing a pattern-formed structure by photolithography, such as a method which includes the processes of: carrying out pattern-exposure of a photoresist layer provided by coating on a base material; developing the photoresist after the exposure; and effecting etching of the developed photoresist layer, and a method which includes the processes of: employing a functional substance as the photoresist; and directly forming the aimed pattern by exposure of the photoresist.
The methods of forming a highly elaborate pattern by lithography have already been employed in formation of a colored pattern of a color filter used in a liquid crystal display or the like, formation of a microlens, production of an elaborate electric circuit board, production of a chrome mask used for pattern exposure, and the like. However, in such methods, it is necessary to use a photoresist, effect development with a liquid developer after exposure and (depending on the method) carrying out etching. Therefore, a problem arises, e.g., in that the waste liquid must be properly treated before discarding. In a case in which a functional substance is used as the photoresist, another problem arises in that the product deteriorates due to the alkali solution used in the development process.
Formation of a highly elaborate pattern such as a color filter by printing has also been attempted. However, a pattern formed by printing tends to cause a problem in the precision of positioning, whereby highly precise pattern formation is difficult by this method.
On the other hand, in order to solve such problems as described above, the inventors of the present invention and other researchers have studied a method of producing a pattern-formed structure in which method a pattern is formed by using a substance whose wetting property is modified by the action of a photocatalyst. However, in such a conventional method of producing a pattern-formed structure by the action of a photocatalyst, the produced pattern-formed structure itself structurally includes the photocatalyst therein, whereby, depending the type of the pattern-formed structure, a problem arises in that the product may deteriorate due to the photocatalyst contained therein.